Background: Ocular syphilis, an inflammatory eye disease, can cause vision loss. Although syphilis is nationally notifiable, ocular manifestations are not. Proportions of syphilis patients with, and risk factors for, ocular syphilis are unknown. Nationally, syphilis rates have increased since 2000, but ocular syphilis clusters were only reported in late 2014. Reports of ocular syphilis in North Carolina increased markedly in 2015. We conducted an investigation to systematically identify ocular syphilis, and determine risk factors, by comparing syphilis cases with and without ocular manifestations.
Methods: We reviewed syphilis cases reported to North Carolina during 2014–2015. Among these, we considered persons with ocular symptoms and signs to have ocular syphilis. We abstracted demographic, risk factor, and sex partner information from health department interviews; characteristics of syphilis cases with and without ocular manifestations were compared using log-binomial regression to estimate prevalence ratios (PRs) and 95% confidence intervals (CIs).
Results: Among 4,234 syphilis patients, 63 (1.5%) had ocular syphilis: 20 in 2014 and 43 in 2015, a 115% increase; syphilis cases increased 35% during this period. Of 59 males, 42 (71%) reported male sex partners. No ocular syphilis patients were identified as sex partners. Patients presented in all syphilis stages; 24 (38%) diagnosed in primary or secondary syphilis. Patients with ocular manifestations were more likely that those without to be male (PR: 2.8; CI:1.0–7.7), white (PR: 2.6; CI:1.6–4.4), aged ≥40 years (PR: 3.3; CI:2.0–5.4) and HIV-infected (PR: 1.8; CI:1.1–2.9). Median RPR tiers for ocular syphilis were higher at every stage. No behavioral risk factors were associated with ocular manifestations.
Conclusions: The increase in ocular syphilis exceeded the rise in reported syphilis cases. Demographic associations may be due to increased access to care, increased recognition or undetected risk factors. Further efforts are ongoing to determine contributing factors and increase awareness.